Spark plugs on a 4.9 1995 Deville

Hello all,
I am the happy owner of a 1995 Deville with the 4.9L engine and my car shows signs of missfiring (shaking, no power,...).
So I went to my mechanic and he told me it would cost about 600$ to do the whole plugs & wires set!!! The reason for this ridiculous price is that apparently it is very hard to get access to rear side plugs on this type of engine...
I'm no mechanic and I trust my guy but still 600 box to change sparks... ugh!

Does anyone know if there is a way to change these sparks myself and thus save like 500$?
I don't have much experience working on cars but if it can save me that much (I'm on a pretty tight budget right now...) I'm totally willing to give it a try! (plus some of my roommates could give me a hand)